System and method for providing and monitoring uv illumination in an interior of an aircraft

ABSTRACT

A system for providing and monitoring UV illumination in an interior of an aircraft includes at least one switchable UV light source; a light detector, responsive to visible light and UV light and configured for providing sensor outputs regarding detected light; and a controller for monitoring an operational status of the at least one switchable UV light source. The controller is configured to determine the operational status of the at least one switchable UV light source by comparing a first sensor output, provided by the light detector when the at least one switchable UV light source is activated, with a second sensor output, provided by the light detector when the at least one switchable UV light source is deactivated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Patent Application No.21188194.1 filed Jul. 28, 2021, the entire contents of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention is in the field of aircraft equipment. The presentinvention is in particular in the field of aircraft disinfection, moreparticularly in the field of aircraft disinfection using ultravioletlight. In the following, ultraviolet light will be referred to as “UVlight”.

BACKGROUND

For reducing the risk of distributing infectious diseases in anaircraft, it is desirable to regularly disinfect surfaces within theaircraft, which are routinely contacted by passengers and/or aircraftpersonnel. UV light may be used as a germicidal illumination fordisinfecting the surfaces within an aircraft by illumination.

It would be beneficial to provide a system and a method which provide aneffective framework for disinfection via UV light in an aircraft.

SUMMARY

According to an exemplary embodiment of the invention, a system forproviding and monitoring germicidal UV illumination in an interior of anaircraft comprises at least one switchable UV light source; a lightdetector, which is responsive to visible light and UV light and which isconfigured for providing sensor outputs regarding detected light; and acontroller for monitoring an operational status of the at least oneswitchable UV light source. The controller is configured for determiningthe operational status of the at least one switchable UV light source bycomparing a first sensor output, provided by the light detector when theat least one switchable UV light source is activated, with a secondsensor output, provided by the light detector when the at least oneswitchable UV light source is deactivated.

According to an exemplary embodiment of the invention, a method forproviding and monitoring germicidal UV illumination in an interior of anaircraft comprises detecting light, which may include visible light andUV light, within the interior of the aircraft, while at least one UVlight source within the interior of the aircraft is deactivated, with alight detector providing a first sensor output; activating the at leastone UV light source; detecting light, which may include visible lightand UV light within the interior of the aircraft, while the at least oneUV light source provided within the interior of the aircraft isactivated, with the light detector providing a second sensor output; andmonitoring an operational status of the at least one switchable UV lightsource, wherein monitoring an operational status of the at least oneswitchable UV light source includes comparing the first sensor outputwith the second sensor output.

Systems and methods providing and monitoring UV illumination in aninterior of an aircraft according to exemplary embodiments of theinvention allow for an efficient and reliable disinfection of surfaceswithin an aircraft using UV light. They may further allow for monitoringand documenting the emission of UV light. This may allow for provingthat sufficient disinfection has been carried out.

Exemplary embodiments of the invention may allow for carrying outdisinfection within an aircraft automatically and for adjusting thedisinfection process to a potential aging and/or deterioration of the atleast one UV light source, which is employed for generating the UVlight.

In an embodiment, the at least one UV light source is configured foremitting UV electromagnetic radiation having a wavelength of less than400 nm, in particular a wavelength in the range of between 150 nm and300 nm, further in particular a wavelength in the range of between 200nm and 270 nm. Electromagnetic radiation having a wavelength in theseranges has been found as highly efficient for disinfection.

In an embodiment, the light detector includes a photo sensor, which issensitive to visible light, and a wavelength converting coating. Thewavelength converting coating emits visible light when being excited byUV light. Such a configuration may allow for using a comparativelyinexpensive photo diode, which is sensitive to visible light, as a photosensor. Further, as the light emitted by the wavelength convertingcoating, when it is excited by UV light, is visible to the human eye,humans may recognized the presence of invisible UV light directly, i.e.without the assistance of a photo sensor, by sensing the visible lightemitted by the wavelength converting coating.

In an embodiment, the wavelength converting coating comprises a lighttransmissive adhesive, in particular a translucent adhesive, which isapplied to the photo sensor, and a wavelength converting substance,which emits visible light when it is excited by UV light. The lighttransmissive adhesive may be a silica based material, for example asilicone or a sodium silicate.

The wavelength converting substance may be applied to an outer surfaceof the light transmissive adhesive, in particular to an outer surfaceopposite to the photo sensor. Such a configuration may allow forilluminating the wavelength converting substance with UV light, withoutthe UV light passing through the adhesive. If the UV light does not haveto pass through the adhesive, there is no risk that the UV light isattenuated or even blocked by the adhesive. Further, the adhesive may beembodied to be light transmissive only to visible light, but not to UVlight. This provides more options for selecting an appropriate adhesive.

In an embodiment, the light transmissive adhesive may include a thinquartz window that encapsulates the wavelength converting substanceunderneath.

In an embodiment, the wavelength converting substance is applied only toa portion of the outer surface of the light transmissive adhesive. Thismay allow visible light to pass through the portions of the lighttransmissive adhesive, to which no wavelength converting substance isapplied, in a particularly unimpeded manner. Such a configuration mayallow the photo sensor to have high sensitivity not only to light, whichis emitted by the wavelength converting substance when its is excited byUV light, but also to visible light incident on the light detector.

Additionally or alternatively, the wavelength converting coating may beapplied to only a portion of a light detecting surface. This may allowvisible light to illuminate surface portions of the photo sensor, whichare not covered by the wavelength converting coating, in a particularlyunimpeded manner.

In an embodiment, the photo sensor is configured for providing spectralinformation about the light detected by the photo sensor. The photosensor may in particular provide information about the intensity of thedetected light as a function of the wavelength of the detected light.Providing spectral information about the light detected by the photosensor may be a particularly effective way of distinguishing between UVlight and visible light illuminating the light detector. As a result,the operation of the UV light source may be monitored very effectivelyand highly reliably.

In an embodiment, the photo sensor comprises a plurality of detectionchannels, wherein the plurality of detection channels have differentsensitivities to different ranges of electromagnetic radiation. As aresult, the photo sensor may be capable to provide separate intensityinformation for each of a plurality of ranges of electromagneticradiation.

In an embodiment, the photo sensor is a multi-color photo sensor,wherein the plurality of detection channels have different sensitivitiesto different ranges of electromagnetic radiation in the range of visiblelight.

In an embodiment, the wavelength converting substance includes aphosphor material. The wavelength converting substance may in particularinclude at least one of Y2O3:Eu3+, Sr2AL6O11:Eu2+, BaMgAl10O17:Eu2+, andLaPO4:Ce3+,TB3+. Y2O3:Eu3+, Sr2AL6O11:Eu2+, BaMgAl10O17:Eu2+, andLaPO4:Ce3+,TB3+ have been found as very suitable and efficient materialsfor converting UV light into visible light.

When excited by UV light, Y2O3:Eu3+ emits red light, in particular redlight having wavelengths in the range of between 605 nm and 615 nm, inparticular red light having wavelengths which are basically centeredaround 611 nm.

When excited by UV light, Sr2AL6O11:Eu2+ emits blue light, in particularblue light having wavelengths in the range of between 425 nm and 475 nm,in particular blue light having wavelengths which are basically centeredaround 450 nm.

When excited by UV light, BaMgAl10O17:Eu2+ emits blue light, inparticular blue light having wavelengths in the range of between 430 nmand 480 nm, in particular blue light having wavelengths which arebasically centered around 455 nm.

When excited by UV light, LaPO4:Ce3+,TB3+ emits green light, inparticular green light having wavelengths in the range of between 520 nmand 570 nm, in particular green light having wavelengths which arebasically centered around 545 nm.

In an embodiment, the wavelength converting substance includes quantumdots for converting UV light into visible light.

In an embodiment, the system is configured for and the method includescontrolling the at least one switchable UV light source based on themonitoring of the operational status of the at least one switchable UVlight source. Controlling the at least one switchable UV light sourcemay in particular include adjusting an intensity of the UV light,emitted by the at least one switchable UV light source, and/or adjustinga period of time, for which the at least one switchable UV light sourceis activated. This may allow for adjusting the operation of the at leastone switchable UV light source so that an efficient and reliabledisinfection of the surfaces, which are illuminated with the UV lightemitted by the UV light source, is ensured.

In an embodiment, the system is provided in a cockpit of an aircraft andit may be configured for illuminating at least one surface, which isusually touched by the pilots, with UV light for disinfection.

In an embodiment, the system is provided in a passenger cabin of anaircraft and it may be configured for illuminating at least one surface,which is usually touched by the passengers and/or cabin crew members,with UV light for disinfection. The system may, for example, beconfigured for illuminating the passenger seats, in particular the armrests and/or the head rests of the passengers seats, and/or passengerservice units (PSUs), which are arranged above the passenger seats, withUV light for disinfection.

In an embodiment, the system is provided in a lavatory and/or in agalley, provided within the passenger cabin of the aircraft, fordisinfecting the lavatory and/or the galley, respectively. Multiple suchsystems may be provided in the lavatories and/or galleys and/or seatingportions of the passenger cabin.

In an embodiment, the system(s) for providing and monitoring UVillumination according to exemplary embodiments of the invention is/areactivated only after the passengers and crew have left the aircraftafter landing, and the system(s) is/are deactivated before newpassengers start boarding the aircraft, so that no people are presentwithin the aircraft when the system(s) is/are activated. Activating thesystem only when no passengers and/or crew members are present withinthe aircraft may prevent humans from being irradiated with UV light.

In an embodiment, system(s) provided in lavatories of the aircraft maybe additionally activated during flight when the lavatories are notoccupied and the doors of the lavatories are closed, so that no UV lightcan exit the lavatory. Systems provided in the lavatories may, forexample, be activated at regular time intervals or after a predefinednumber of passengers have used the respective lavatory, in order toensure hygienic conditions within the lavatories during the flight.

In an embodiment, controlling the at least one switchable UV lightsource includes adjusting the intensity of UV light emitted by the atleast one switchable UV light source by controlling the operation of theUV light source. The intensity of UV light emitted by the at least oneUV light source may, for example, be adjusted so that the intensity ofthe UV light is within a predefined range between a predefined minimumintensity and a predefined maximum intensity.

In an embodiment, controlling the at least one switchable UV lightsource includes adjusting a period of time, for which the at least oneswitchable UV light source is activated. The period of time, for whichthe at least one switchable UV light source is activated, may inparticular be adjusted as a function of the detected intensity of UVlight.

For example, the period of time, for which the at least one switchableUV light source is activated, may be extended when the detected UVintensity is low, and the period of time, for which the at least oneswitchable UV light source is activated, may be shortened when thedetected UV intensity is high, in order to achieve a substantiallyconstant disinfection effect, independent of potential changes of theintensity of the UV light. The intensity of the UV light may vary forexample due to aging of the at least one UV light source, due tocontamination of the UV light source, etc.

In an embodiment, the controller is configured for calculating anindication regarding a total amount of UV light, which is emitted by theat least one switchable UV light source over time, by accumulating thesensor outputs over time. The controller may further be configured forproviding a confirmation signal when the indication exceeds a predefinedthreshold. The confirmation signal may include a visual and/or anacoustic signal.

Such a configuration may allow for indicating that an amount of UVlight, which is considered as sufficient for reliably disinfecting atleast one surface illuminated with the UV light, has been detected.

The confirmation signal may also be employed as a control signal, whichcauses the at least one switchable UV light source to be deactivated.This may allow for automatically deactivating the at least oneswitchable UV light source, after a sufficient amount of UV light hasbeen emitted. In consequence, surfaces within the aircraft may bedisinfected automatically without human intervention and withoutexcessive use of UV light.

In an embodiment, the confirmation signal includes a signal which istransmitted to a board computer of the aircraft and/or a report/logsignal, which allows for logging the operation of the at least one UVlight source. Logging the operation of the at least one UV light sourcemay allow for documenting that surfaces within the aircraft have beendisinfected regularly and sufficiently.

Logging the operation of the at least one UV light source may furtherallow for monitoring the periods of operational time of the at least oneUV light source needed for sufficient disinfection. An increase of theperiods of operational time needed for sufficient disinfection mayindicate an aging of the at least one UV light source. In consequence,an aging UV light source may be replaced in good time before itcompletely fails or becomes too weak for reliable disinfection.

BRIEF DESCRIPTION OF DRAWINGS

Further exemplary embodiments of the invention are described below withrespect to the accompanying drawings, wherein:

FIG. 1 depicts an aircraft, in particular an air plane, in accordancewith an exemplary embodiment of the invention in a schematic side view;

FIG. 2 depicts a schematic view of an overhead passenger service unit(PSU);

FIG. 3 depicts a schematic cut-open view of an aircraft in accordancewith an exemplary embodiment of the invention, depicting a passengercabin of the aircraft;

FIG. 4 depicts a schematic view of a system for providing and monitoringUV illumination according to an exemplary embodiment of the invention;

FIG. 5 shows a schematic cross-sectional view of a light detector, as itmay be employed in a system according to an exemplary embodiment of theinvention;

FIG. 6A shows the light intensities, detected by the light detector, asa function of the wavelength, when the at least one UV light source isswitched off; and

FIG. 6B shows the light intensities, detected by the light detector, asa function of the wavelength, when the at least one UV light source isswitched on.

DETAILED DESCRIPTION

FIG. 1 shows an aircraft 100, in particular an air plane, in accordancewith an exemplary embodiment of the invention in a schematic side view.In the exemplary embodiment shown in FIG. 1 , the aircraft 100 is alarge passenger air plane, comprising a cockpit 103 and a passengercabin 104 housing a plurality of passenger seats 106. The aircraft 100may be a commercial passenger air plane, a private air plane, or amilitary aircraft. It is also possible that the system and methodaccording to exemplary embodiments of the invention are implemented in arotorcraft, such as a helicopter.

Passenger service units (PSU) 102 are arranged above the passenger seats106.

In an exemplary configuration, in which the aircraft 100 comprises sixpassenger seats 106 per row (cf. FIG. 3 , which will be discusses inmore detail further below), each row of passenger seats 106 may have twopassenger service units 102 associated therewith, one passenger serviceunit 102 assigned to the passenger seats 106 on the left side of acenter aisle 114 and one passenger service unit 102 assigned to thepassenger seats 106 on the right side of the center aisle 114.

FIG. 2 depicts a schematic view of an overhead passenger service unit(PSU) 102, which is arranged above the passengers of a single passengerrow, as it is seen from the side of a passenger sitting on a passengerseat 106 below the overhead passenger service unit 102.

On the side, which is shown to the left in FIG. 2 , the overheadpassenger service unit 102 comprises a row of three adjustable readinglights 26 a-26 c, which are arranged next to each other.

Six electrical switches 27 a-27 c, 28 a-28 c are provided to the rightside of the reading lights 26 a-26 c, a respective pair of two switches27 a-27 c, 28 a-28 c next to each of the reading lights 26 a-26 c. Oneof the switches 27 a-27 c of each pair is configured for switching theadjacent reading light 26 a-26 c, and the second switch 28 a-28 c ofeach pair is configured for triggering a signal for calling cabinservice personnel.

A row of three adjacent gaspers 29 a-29 c is provided next to theswitches 27 a-27 c, 28 a-28 c.

Adjacent to the gaspers 29 a-29 c is a removable cover 40, which coversa cavity housing at least three oxygen masks (not shown). In the eventof pressure loss within the cabin, the removable cover 40 will open, theoxygen masks will drop out of the cavity and each of the passengers,sitting below the overhead passenger service unit 102, may grasp one ofthe oxygen masks. The oxygen masks will be supplied with oxygen allowingthe passengers to continue to breathe normally.

On the side opposite to the gaspers 29 a-29 c, a grid 42 is formedwithin overhead passenger service unit 102. A loudspeaker (not shown),which may be used for delivering acoustic announcements to thepassengers, is arranged behind said grid 42.

Next to the grid 42, there is a display panel 44, which may beconfigured for selectively showing a plurality of visual signs (notshown), such as “non smoking” or “fasten you seat belt”. The displaypanel 44 may be illuminated from behind, in order to deliver visualinformation to the passengers sitting below the overhead passengerservice unit 102.

FIG. 3 depicts a schematic cut-open view of an aircraft 100 inaccordance with an exemplary embodiment of the invention, depicting apassenger cabin 104 of the aircraft 100, also referred to as aircraftpassenger cabin 104 herein.

The aircraft passenger cabin 104 is equipped with a plurality ofpassenger seats 106. The passenger seats 106 are arranged next to eachother forming a plurality of passenger seat rows. Each passenger seatrow comprises two groups of passenger seats 106, respectively includingthree passenger seats 106. The two groups of passenger seats 106 areseparated from each other by a center aisle 114, extending along alongitudinal axis A of the aircraft 1.

The aircraft passenger cabin 104 is further equipped with fourlavatories 108 a-108 d. In the exemplary configuration depicted in FIG.3 , lavatories 108 a-108 d are provided at four locations within theaircraft passenger cabin 104. A first lavatory 108 a is located at thefront portside end of the aircraft passenger cabin 104, a secondlavatory 108 b is located at the front starboard end of the aircraftpassenger cabin 104, a third lavatory 108 c is located at the rearportside end of the aircraft passenger cabin 104, and a fourth lavatory108 d is located at the rear starboard end of the aircraft passengercabin 104. Additionally or alternatively, lavatories 108 a-108 d may beprovided at other locations of the aircraft passenger cabin 104 as well.

The aircraft passenger cabin 104 is further equipped with a galley 110,in order to allow for preparing meals and drinks for the passengers.

At least one of the lavatories 108 a-108 d and the galley 110 isprovided with a system 2 for providing and monitoring UV illuminationaccording to an exemplary embodiment of the invention.

In the exemplary embodiment depicted in FIG. 3 , each lavatory 108 a-108d and the galley 110 are provided with a system 2 for providing andmonitoring UV illumination, respectively. However, exemplary embodimentsof the invention also include aircraft 100 in which only one or anysubset of the lavatories 108 a-108 d and the galley 110 are providedwith a system 2 for providing and monitoring UV illumination.

Although not explicitly depicted in FIG. 3 , systems 2 for providing andmonitoring UV illumination according to exemplary embodiments of theinvention may also be provided next to the passenger service units 102(cf. FIGS. 1 and 2 ) for disinfecting said passenger service units 102by illuminating the passenger service units 102 with UV light.

Systems 2 for providing and monitoring UV illumination according toexemplary embodiments may also be provided within the passenger cabin104 for illuminating and disinfecting the passenger seats 106 locatedunder the passenger service units 102. The systems 2 may, for example,be integrated into the passenger service units 102 or arranged next tothe passenger service units 102.

Systems 2 for providing and monitoring UV illumination according toexemplary embodiments of the invention may also be provided within thecockpit 103 of the aircraft 100 for disinfecting surfaces touched by thepilots.

As UV light may be harmful to humans, in particular to the human eye,the systems 2 for providing and monitoring UV illumination according toexemplary embodiments provided within the passenger cabin 104 and/orwithin the cockpit 103 of the aircraft 100 may be activated only afterthe passengers and crew have disembarked after the flight, so that nohumans are present within the aircraft 100.

Systems 2 for providing and monitoring UV illumination according toexemplary embodiments located in the lavatories 108 a-108 d, however,may also be activated during flight, when the lavatories 108 a-108 d arenot occupied and the doors of the lavatories 108 a-108 d are closed, sothat no UV light can exit the lavatories 108 a-108 d. Systems 2 locatedwithin the lavatories 108 a-108 d may, for example, be activated inregular time intervals or after a predefined number of passengers haveused the respective lavatory 108 a-108 d, in order to ensure hygienicconditions within the lavatories during the flight.

A schematic view of a system 2 for providing and monitoring UVillumination according to an exemplary embodiment of the invention isdepicted in FIG. 4 .

The system 2 comprises at least one lighting device 4, which isconfigured for emitting visible light for illuminating the environmentof the system 2, for example the lavatory 108 a-108 d or the galley 110.In the exemplary embodiment depicted in FIG. 4 , two lighting devices 4are shown. Each lighting device 4 may comprises at least one LED actingas a light source. Each lighting device 4 may in particular comprise aplurality of light sources 4 a-4 c, which are configured for emittinglight of different colors. Such a configuration may allow for adjustingthe color of the light, emitted by the at least one lighting device 4,by varying the intensity of the light emitted by the different lightsources 4 a-4 c. In the exemplary embodiment of FIG. 4 , each of theplurality of light sources 4 a-4 c comprises one or more LED(s).

The system 2 further comprises at least one switchable UV light source6, which is configured for emitting UV light when activated. The UVlight emitted by the at least one UV light source 6 may be directed toat least one surface for disinfecting said at least one surface, usingthe germicidal properties of UV light. The at least one UV light source6 may include at least one LED, which is configured for emitting UVlight.

The UV light emitted by the at least one UV light source 6 may have awavelength of less than 400 nm, in particular a wavelength in the rangeof between 150 nm and 300 nm, more particularly a wavelength in therange of between 200 nm and 270 nm.

The system 2 further comprises a light detector 8 and a controller 10.

The light detector 8 is responsive to visible light and to UV light andis configured for providing sensor outputs, representing the detectedlight, to the controller 10.

The controller 10 is configured for monitoring an operational status ofthe at least one switchable UV light source, based on sensor outputsreceived from the light detector 8, and for selectively activating anddeactivating the at least one lighting device and the at least one UVlight source 6.

The controller 10 is in particular configured for activating the atleast one UV light source 6 and for receiving a first sensor output,provided by the light detector 8 while the at least one UV light source6 is activated. The controller 10 is further configured for deactivatingthe at least one switchable UV light source 6 and for receiving a secondsensor output, which is provided by the light detector 8 while the atleast one UV light source 6 is deactivated.

Alternatively, the controller 10 may be configured for receiving a firstsensor output, which is provided by the light detector 8 while the atleast one UV light source 6 is deactivated; for activating the at leastone switchable UV light source 6; and for receiving a second sensoroutput, which is provided by the light detector 8 while the at least oneUV light source 6 is activated.

The controller 10 monitors the operational status of the at least oneswitchable UV light source 6 by comparing the first and second sensoroutputs with each other. The controller 10 is further configured forcontrolling the at least one switchable UV light source 6 based on saidmonitoring of the operational status of the at least one switchable UVlight source 6.

Details of different modes of operation will be discussed in more detailfurther below.

FIG. 5 shows a schematic cross-sectional view of a light detector 8, asit may be employed in a system 2 according to an exemplary embodiment ofthe invention.

The light detector 8 includes a photo sensor 80 sensitive to visiblelight, which is mounted to a support 81, for example to a printedcircuit board 81.

The photo sensor 80 may in particular be configured for providingspectral information about the light detected by the photo sensor 80,i.e. the photo sensor 80 may provide information about the intensity ofthe detected light as a function of the wavelength of the detectedlight.

The photo sensor 80, for example, may comprise a plurality of detectionchannels, with the plurality of detection channels having differentsensitivities to different ranges of electromagnetic radiation, so thatthe photo sensor 80 is capable to provide separate intensity informationfor each range of electromagnetic radiation, respectively.

The photo sensor 80 may, for example, be a multi-color photo sensor,wherein the plurality of detection channels have different sensitivitiesto different ranges of electromagnetic radiation in the range of visiblelight, e.g. in the range between 350 nm and 800 nm.

In order to allow the photo sensor 80 to detect UV light, the photosensor 80 may be at least partially covered with a wavelength convertingcoating 82, which is configured for emitting visible light when it isexcited by UV light.

In the embodiment depicted in FIG. 5 , the wavelength converting coating82 includes a translucent adhesive 84, which is applied to an uppersurface of the photo sensor 80 on a side opposite to the support 81, anda wavelength converting substance 86, which is applied to a side of theadhesive 84 facing away from the photo sensor 80.

The wavelength converting substance 86 may cover the upper surface ofthe adhesive 84 facing away from the photo sensor 80 completely.Alternatively, the wavelength converting substance 86 may cover theupper surface of the adhesive 84 only partly, in order to allow visiblelight to pass through portions of the translucent adhesive 84, which arenot covered by the wavelength converting substance 86, in an unimpededmanner.

In an alternative embodiment, which is not explicitly shown in thefigures, the light transmissive adhesive 84 may include a thin quartzwindow that encapsulates the wavelength converting substance 86underneath.

The wavelength converting substance 86 may include a phosphor material,in particular at least one of Y2O3:Eu3+, Sr2AL6O11:Eu2+,BaMgAl10O17:Eu2+, and LaPO4:Ce3+,TB3+. These phosphor materials havebeen found as well suited for converting UV light into visible light.

The wavelength of the visible light, into which the UV light isconverted, depends on the material used for the wavelength convertingsubstance 86. In other words, the wavelength of the visible light, intowhich the UV light is converted, may be selected by choosing thematerial of the wavelength converting substance 86.

Y2O3:Eu3+, for example, converts UV light very efficiently into visiblered light having a wavelength of approximately 611 nm. Sr2AL6O11:Eu2+and BaMgAl10O17:Eu2+ convert UV light to visible blue light, andLaPO4:Ce3+,TB3+ emits visible green light, when it is excited by UVlight.

All these materials emit a very narrow spectrum of visible light, i.e. aspectrum of visible light in which at least 90% of the light is emittedwithin a range of wavelengths having a width of 50 nm. Providing such anarrow spectrum of visible light may allow for reliably detecting andidentifying the converted visible light, which is emitted by thewavelength converting substance 86, when it is excited by UV light.

Alternatively or additionally to a phosphor material, as it has beendescribed before, the wavelength converting substance 86 may includequantum dots for converting the UV light, emitted by the at least one UVlight source 6, into visible light, which is detectable by the photosensor 80.

FIGS. 6A and 6B illustrate examples of light intensities I, plotted onthe vertical axis, as detected by the light detector 8 when the at leastone UV light source 6 is switched off (FIG. 6A) and when the at leastone UV light source 6 is switched on (FIG. 6B). The light intensities Iare depicted as a function of the wavelength λ, which is plotted on thehorizontal axis.

FIG. 6A depicts the spectral distribution of the light emitted by the atleast one lighting device 4 comprising three peaks 91, 92, 93, namely afirst peak 91 centered at approximately 465 nm corresponding to bluelight, a second peak 92 centered at approximately 555 nm correspondingto green light, and a third peak 93 centered at approximately 611 nmcorresponding to red light.

A spectral distribution, as it is depicted in FIG. 6A, is detected andstored when the at least one UV light source 6 is deactivated. Inaddition to light emitted by the at least one lighting device 4 providedwithin the aircraft 100, the spectral distribution may include furtherspectral components (not shown), which may result from external light,in particular sun light, which enters through windows into the aircraft100.

FIG. 6B depicts the spectral distribution of the light detected by thelight detector 8 when the at least one UV light source 6 is activatedand the UV light, emitted by the at least one UV light source 6, isconverted into visible light, in particular into red light having awavelength spectrum centered around 611 nm, by Y2O3:Eu3+, which has beenapplied to the surface of the photo sensor 80 as the wavelengthconverting substance 86.

The comparison of FIGS. 6A and 6B shows that the first and second peaks91, 92, corresponding to blue light and green light, do not change whenthe at least one UV light source 6 is activated. The height of the thirdpeak 93, corresponding to the intensity of detected red light, however,increases considerably when the at least one UV light source 6 isactivated. In the examples depicted in FIGS. 6A and 6B, the height ofthe third peak 93 almost doubles when the at least one UV light source 6is activated.

This drastic increase ΔI of the detected intensity of red light allowsthe controller 10 to reliably confirm that the at least one UV lightsource 6 is activated. It further allows the controller 10 to determinean indication regarding the intensity of the UV light, emitted by the atleast one UV light source 6, from the change of the height of the thirdpeak 93.

In case a different material than Y2O3:Eu3+ is employed as thewavelength converting substance 86 for converting the UV light, emittedby the least one UV light source 6, into visible light, the first peak91 and/or the second peak 92, corresponding to blue light and greenlight, respectively, may increase instead of or in addition to the thirdpeak 93.

In particular, if Sr2AL6O11:Eu2+ or BaMgAl10O17:Eu2+ are included in thewavelength converting substance 86, the first peak 91 corresponding toblue light will increase, and the second peak 92 corresponding to greenlight will increase if LaPO4:Ce3+,TB3+ is included in the wavelengthconverting substance 86.

By comparing a first sensor output, provided by the light detector 8when the at least one switchable UV light source 6 is activated, as itits depicted in FIG. 6B, with a second sensor output, which is providedby the light detector 8 when the at least one switchable UV light source6 is deactivated, as it is depicted in FIG. 6A, the controller 10 iscapable to reliably determine whether the at least one switchable UVlight source 6 has been activated. This may be true even under varyingambient light conditions. The ambient light conditions may, for example,change due to a change of external light, in particular sun light,shining into the aircraft 100.

The controller 10 is further capable to determine an indicationregarding the intensity of the UV light and to control the operation ofthe at least one UV light source 6 based on the information about theintensity of the UV light, provided by the light detector 8.

Controlling the at least one switchable UV light source 6 may includeadjusting the intensity of UV light, emitted by the at least oneswitchable UV light source 6, by controlling the operation of the atleast one UV light source 6. The intensity of UV light, emitted by theat least one UV light source 6, may for example be adjusted so that theintensity of the UV light exceeds a predefined minimum intensitythreshold and/or so that the intensity does not exceed a predefinedmaximum intensity threshold.

Controlling the at least one switchable UV light source 6 may alsoinclude adjusting a period of time, for which the at least oneswitchable UV light source 6 is activated. The period of time, for whichthe at least one switchable UV light source 6 is activated, may inparticular be changed as a function of the detected intensity of UVlight.

For example, the period of time, for which the at least one switchableUV light source 6 is activated, may be extended when the detected UVintensity is low, and the period of time, for which the at least oneswitchable UV light source 6 is activated, may be shortened when thedetected UV intensity is high. In this way, a substantially constantdisinfection effect may be achieved, independent of potential changes inthe intensity of the UV light, which may occur for example due to agingof the at least one UV light source 6.

The controller 10 may, for example, be configured for calculating anindication regarding a total amount of UV light, which is emitted by theat least one switchable UV light source 6 over time, by accumulating thesensor outputs over time. The controller 10 may further be configuredfor providing a confirmation signal, when the indication exceeds apredefined threshold. The confirmation signal may include a visualand/or an acoustic signal. The confirmation signal may also include acontrol signal, which causes deactivating the at least one switchable UVlight source.

Such a configuration may allow for indicating that an amount of UVlight, which is considered sufficient for reliably disinfecting at leastone surface by illumination with UV light, has been detected. It mayfurther allow for automatically deactivating the at least one switchableUV light source after a sufficient amount of UV light has been detected.This may allow for a reliable automatic disinfection of surfaces withinthe aircraft 100.

Optionally, the confirmation signal may further include a signal whichis transmitted to a board computer of the aircraft 100 and/or a logsignal, which allows for logging the operation of the at least one UVlight source 6. Logging the operation of the at least one UV lightsource 6 may allow for documenting that surfaces within the aircraft 100have been disinfected regularly and sufficiently.

Logging the operation of the at least one UV light source 6 may furtherallow for monitoring the periods of operational time of the at least oneUV light source 6 needed for sufficient disinfection. An increase of theperiods of operational time needed for sufficient disinfection mayindicate an aging of the at least one UV light source 6. In consequence,an aged UV light source 6 may be replaced in good time before itcompletely fails or becomes too weak for allowing a reliabledisinfection.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A system for providing and monitoring UV illumination in an interiorof an aircraft, the system comprising: at least one switchable UV lightsource; a light detector, responsive to visible light and UV light andconfigured for providing sensor outputs regarding detected light; and acontroller for monitoring an operational status of the at least oneswitchable UV light source, wherein the controller is configured todetermine the operational status of the at least one switchable UV lightsource by comparing a first sensor output, provided by the lightdetector when the at least one switchable UV light source is activated,with a second sensor output, provided by the light detector when the atleast one switchable UV light source is deactivated.
 2. The systemaccording to claim 1, wherein the light detector includes a photosensor, which is sensitive to visible light, and a wavelength convertingcoating, with the wavelength converting coating emitting visible lightwhen being excited by UV light.
 3. The system according to claim 2,wherein the photo sensor comprises a plurality of detection channels,with the plurality of detection channels having different sensitivitiesto different ranges of electromagnetic radiation, wherein the photosensor is in particular a multi-color photo sensor, with the pluralityof detection channels having different sensitivities to different rangesof electromagnetic radiation in the range of visible light.
 4. Thesystem according to claim 2, wherein the wavelength converting coatingcomprises a light transmissive adhesive, in particular a translucentadhesive, and wherein a wavelength converting substance is adhered tothe photo sensor via the light transmissive adhesive.
 5. The systemaccording to claim 4, wherein the wavelength converting substanceincludes a phosphor material that is at least one ofY₂O₃:Eu³⁺,Sr₂Al₆O₁₁:Eu²⁺, BaMgAl₁₀O₁₇:Eu²⁺, and LaPO₄:Ce³⁺,TB³⁺.
 6. Thesystem according to claim 4, wherein the wavelength convertingsubstance, when excited with UV light, emits visible light in the rangeof between 600 nm and 650 nm.
 7. The system according to claim 1,wherein the light detector includes quantum dots.
 8. The systemaccording to claim 1, wherein the system is configured for controllingthe at least one switchable UV light source based on said monitoring ofthe operational status of the at least one switchable UV light source;wherein controlling the at least one switchable UV light source inparticular includes adjusting an intensity of UV light, emitted by theat least one switchable UV light source, or adjusting a period of time,for which the at least one switchable UV light source is activated. 9.The system according to claim 1, wherein the system is configured forcalculating an indication regarding a total amount of UV light, emittedby the at least one switchable UV light source over time, byaccumulating the sensor outputs over time, and wherein the system isconfigured for providing a confirmation signal, when the indicationregarding the total amount of UV light exceeds a predefined threshold;wherein the confirmation signal is in particular a visual confirmationsignal and an acoustic confirmation signal, and/or wherein the system isconfigured for deactivating the at least one switchable UV light source,when the confirmation signal is issued.
 10. An aircraft comprising: atleast one system for providing and monitoring UV illumination accordingto claim 1, wherein the at least one system is located in at least oneof a cockpit and a passenger cabin of the aircraft.
 11. The aircraft ofclaim 10, wherein the at least one system is located in a lavatory or ina galley provided within the passenger cabin of the aircraft.
 12. Amethod of providing and monitoring UV illumination in an interior of anaircraft, the method comprising: detecting light within the interior ofthe aircraft with a light detector, while at least one switchable UVlight source is deactivated, and providing a first sensor output, whichis a function of the detected light; activating the at least oneswitchable UV light source; detecting light within the interior of theaircraft with the light detector, while the at least one switchable UVlight source is activated, and providing a second sensor output, whichis a function of the detected light; and monitoring an operationalstatus of the at least one switchable UV light source, whereinmonitoring an operational status of the at least one switchable UV lightsource includes comparing the first sensor output with the second sensoroutput.
 13. The method according to claim 12, wherein the light isdetected by a light detector comprising at least one photo sensor, whichis sensitive to visible light, and a wavelength converting coating,which emits visible light when it is excited by UV light.
 14. The methodaccording to claim 11, wherein the method includes: controlling the atleast one switchable UV light source based on said monitoring of theoperation status of the at least one switchable UV light source; whereincontrolling the at least one switchable UV light source in particularincludes adjusting an intensity of light, emitted by the at least oneswitchable UV light source, or adjusting a period of time, for which theat least one switchable UV light source is activated.
 15. The methodaccording to claim 12, wherein the method includes: calculating anindication regarding a total amount of UV light, emitted by the at leastone switchable UV light source, by accumulating the sensor outputs overtime and providing a confirmation signal, when the calculated indicationexceeds a predefined threshold; wherein the confirmation signal is inparticular a visual confirmation signal or an acoustic confirmationsignal, or wherein the method includes deactivating the at least oneswitchable UV light source, when the confirmation signal has beenissued.
 16. The method according to claim 12, wherein the methodincludes: illuminating portions of a cockpit or of a passenger cabin ofan aircraft with the UV light emitted by the at least one switchable UVlight source.
 17. The method of claim 16, wherein illuminating includesilluminating portions of at least one of a lavatory, a galley, and apassenger service unit, located within the passenger cabin, with the UVlight.